This invention claims the benefit of Japanese Patent Application No. HEI 2000-097018, filed on Mar. 31, 2000, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a vehicle lamp for use in the illumination of a headlamp, fog lamp etc., and more particularly relates to a vehicle lamp that forms a light distribution characteristic in a multi-reflex manner using an ellipse group reflector and a parabolic group reflector.
2. Description of the Related Art
FIG. 8 shows a conventional vehicle headlight 90 that includes a parabolic group reflecting surface 91, such as a rotated parabolic surface. FIG. 9 shows another conventional vehicle headlight 80 that includes an elliptic group reflecting surface 81, such as a rotated elliptic surface.
The conventional vehicle headlight 90 includes a parabolic group reflecting surface 91, such as a rotated parabolic surface, having a focus f and rotation axis of an optical axis X, i.e., an illumination direction of the conventional headlight 90. The headlight 90 also includes a light source 92, such as a filament, located in a front vicinity of and at a predetermined distance from the focus f of the parabolic group reflecting surface 91. A shade 92a is included for forming low-beam light distribution patterns. Due to the positioning of the light source 92, light reflected by an upper half of the reflecting surface 91 is directed downward. The shade 92a covers a lower half of the light source 92 to prohibit certain light rays from being directed towards a lower half of the parabolic group reflecting surface 91. The certain light rays would be upwardly directed light rays after being reflected by the lower half of the parabolic group reflecting surface 91.
The conventional vehicle headlight 80 includes an elliptic group reflecting surface 81, such as a rotated elliptic surface, having a first focus f1 and a second focus f2, a light source 82 located on the first focus f1, a shading plate 83 located in the vicinity of the second focus f2, and a projection lens 84 having its focus in the vicinity of the second focus f2. Light reflected by the elliptic group reflecting surface 81 converges to the second focus f2. An image of luminous flux at the second focus f2 is projected upside-down in the illumination direction X by the projection lens 84. When the headlight 80 is placed into low-beam mode, the shading plate 83 prohibits a portion of luminous flux from converging at the second focus f2 such that a predetermined shape of a low-beam light distribution pattern for the vehicle headlight 80 is provided.
Conventional vehicle headlights 90 and 80 have the following problems. First, the conventional vehicle headlights 90 and 80 have little design flexibility. In the conventional vehicle headlights 90 and 80, light emitted at all directions from the light source 92 or 82 is reflected into illumination direction X of the headlight 90 or 80 by the parabolic group reflecting surface 91 or the elliptic group reflecting surface 81 to determine the light distribution patterns of the headlights 90 or 80. Accordingly, either the length or width (as viewed from the front of headlights 80 or 90) must be larger than 70 mm to provide a sufficient amount of light. If either of the length or width dimensions is equal to or smaller than 70 mm, the utilization efficiency of luminous flux emitted from light source by the reflecting surfaces 91 or 81 greatly decreases, and it is substantially impossible to function as a headlight. In addition, the conventional vehicle headlights 90 and 80 include a shade 92a and a shading plate 83, respectively. The shade 92a and the shading plate 83 prohibit substantially half of the total light amount from the light sources 92 and 82. Therefore, it has been a goal with conventional lights to improve utilization efficiency of lumen output in the low-beam light distribution pattern. The low-beam light distribution is usually employed at night-time while the traveling light distribution (high-beam mode) is usually employed during the day, during a drive on the highway, or in desolate areas.
In order to resolve the aforementioned and other problems in the related art, the present invention provides a vehicle light that can include a light source, and at least one first elliptic group reflecting surface that is shaped as a substantial half of an elliptic surface, i.e., the portion that remains after either an upper or lower substantial half of the ellipse is removed. The reflector can have a longitudinal axis on an optical axis of the vehicle light and a first focus in vicinity of the light source. Two second elliptic group reflecting surfaces can be provided and shaped as substantial halves of elliptic surfaces, i.e., the portions that remain after either upper or lower substantial halves of the ellipses are cut-off (both of which substantially correspond to the shape of the first elliptic group reflecting surface). The second elliptic group reflecting surfaces can have longitudinal axes that are substantially horizontally perpendicular to the optical axis of the vehicle light and first foci located in the vicinity of the light source. The vehicle light can also include two third parabolic group reflecting surfaces, each having its optical axis in a direction parallel to the optical axis of the vehicle lamp and its focus in the vicinity of a second focus of each second elliptic group reflecting surface.